Several methods for three-dimensional reconstruction of surfaces of microscopic structures are known. In CLSM (confocal laser scanning microscopy) the specimen is scanned point by point in one plane, and an image with very little depth of focus is thereby acquired. With a plurality of images in different planes, and by way of appropriate image processing, the specimen can be depicted three-dimensionally. In CLSM the data can be generated only in very expensive fashion, and high-quality optical components are a prerequisite. A high level of technical complexity is also necessary in another technique in which a 3D reconstruction is achieved by means of a thin line of light directed onto the surface that is to be reconstructed.
Chen J. mentiones in his PhD thesis, City University, UK. February, 1995, “The Use of Multiple Cameras and Geometric Constraints for 3-D measurement”.
The German Patent Application DE 101 49 357 discloses a method and an apparatus for optical measurement of a surface profile of a specimen. A series of n images of the specimen being acquired with an image acquisition apparatus in different planes in the z direction of a coordinate system (x, y, z). The image contents of all n images of the resulting image stack are compared to each other in the z direction at each coordinate point (x, y) in order to determine a plane therefrom according to predetermined criteria, assign its plane number (N) to that coordinate point (x, y), and store it in a mask image. The mask image contains all the 3D data of the specimen surface. Processing can be performed using 2D image processing procedures. The 3D information can be quickly and easily retrieved from the mask image. The surface profile can be reconstructed and displayed three-dimensionally. The disclosed system does not include any correction of distortions in multi-focus image stacks.
The U.S. Pat. No. 6,148,120 uses image processing to alter the spatial relationship in one or more focal images in order to ensure geometric correspondence between the images. The image processing is composed of two fundamental processes: mapping and resampling. In mapping, the spatial relationship between the input image coordinates and the processed (output) image coordinates is established. In resampling, image value interpolated from pixels from the input image are written to corresponding locations in the output image according to the mapping. The prior art relies on exact knowledge of geometry compared with proposed method, wherein the correction is determined by matching adjacent images. Additionally, no correction for radiometric variations from layer to layer is disclosed or mentioned.
The U.S. Pat. No. 6,313,452 discloses a microscopy system utilizing a plurality of images for enhanced image processing capabilities. The microscopy system comprising a microscope including a stage, at least one magnifying lens, and a lens controller, a video capture device coupled to the microscope capturing a plurality of images of an object on the stage of the microscope and a processing subsystem receiving the plurality of images from the video capture device, in which the processing subsystem generates at least one resultant image as a function of the plurality of images. The at least one resultant image generated by the processing subsystem may include a mosaic, submosaic or a sequence of mosaics. The system is not capable in talking multifocus images.